EP0780142A1 - Snowboard with stiffening device - Google Patents

Abstract

The ski/snow-board has a sliding lower surface, an upper surface (10) with boot fastenings (4,5), and a regulator to control the rigidity of the board with foot pressure. The regulator consists of a platform (2) with the boot fastenings, a central support with a pivot (8), and cams (14,16,18,19) at each end which help to vary the curvature of the board's sliding surface. The cams are located on the upper surface of the board and the under surface of the platform and have facing sloping surfaces which can be coated with a material with a low friction coefficient, e.g. PTFE. Alternatively, one of the cams in each pair can be in the form of a cylindrical roller. Alternatively, the rear end of the platform can be connected to the upper surface of the board by a rigid strip, e.g. of aluminium, or the rear portion of the platform can be supported by a rigid or semirigid plate of a visco-elastic material with a minimum Shore A hardness of 80.

Description

Technical area

The invention relates to the field of snow sliding sports. It relates more particularly to gliding boards equipped with a device interposed between the binding and the top of the board making it possible to adapt, interactively, the characteristics of the board to the different positions and intensities of the pulse forces observed during of the practice of sport, especially during the making of a turn.

Subsequently, the invention will be described in its more particular application to alpine skiing, without it being necessary to exclude from the scope of the invention the other snow sliding sports such as monoskiing or snowboarding.

Previous techniques

The invention in particular aimed at optimizing the behavior of a ski when making a turn, it is necessary beforehand to specify the different phases and the position of the forces transmitted by the skier to the ski during a turn. Very schematically, a turn can be broken down into three essential phases, namely the initiation, driving and exiting of the turn.

During the initiation phase of the turn, the skier carries his body weight towards the inside of the turn and towards the front. The ski must then bend to register its internal edge in a curve. To decrease the radius of curvature of this trajectory, the skier's impulse, that is to say the force he exerts on the ski, must be greater than to make a turn with a large radius. It has been observed that the impulse exerted can reach a force corresponding to five to eight times the weight of the skier. To facilitate the curvature of the ski during this triggering phase, the ski must be sufficiently flexible and the application of the skier's load on the ski must be practically punctual, in order to obtain short ski behavior.

During the driving phase of the turn, the skier's position recedes so that the weight of his body is applied practically at the level of the middle of the boot. In this phase, the ski maintains its radius of curvature.

Finally, at the end of the turn, the skier moves his body weight backwards, so the skier's support area on the ski moves in the direction of the heels of the boots. During this phase, it is preferable to have a stiffer ski, behaving like a ski of greater length in order to improve its stability. In this phase, the weight of the skier must be distributed over the maximum length of the ski.

It is therefore understandable that, ideally, the ski should behave like a short and very flexible ski when initiating and driving the turn, then transform into a long and stiff ski for the driving phase.

Document FR-A-2 702 386 of the applicant describes a hydraulic device allowing, depending on the front or rear location of the skier's thrust, the modification of the general stiffness of the ski. Although satisfactory and giving appreciated results, this solution needs to be implemented within the thickness of the ski, which requires relatively complex operations which are economically unprofitable.

There have also been proposed in the documents FR-A-2 684 885, FR-A 2 686 798, FR-A-2 686 799, FR-A-2 690 079 and FR-A-2 713 945, devices intended for modify the natural pressure distribution of a ski on its sliding surface. These devices are installed under the sole of the boot, between the toe and the heel of the binding and allow a system of arms, levers and rockers actuated during the booting of the shoe to exert tension on the ski. Unfortunately, this device requires a large number of parts which have particularly stressed articulation axes, and therefore fragile especially under the conditions of use (humidity and cold) and moreover generating mechanical play. In addition, they do not dynamically change the stiffness of the ski depending on the position of the skier. They practically do not vary the stiffness of the ski in use, depending on the location of the supports exerted by the skier. These devices modify the stiffness of the ski and its camber as soon as the boot is placed in the binding, only by applying the load on the heels of the boots.

The problem which the invention proposes to solve is to provide a ski whose stiffness changes dynamically during the different phases of the turn. The aim is to give the ski a behavior equivalent to that of a short and flexible ski during the front rests at the start of the turn, and alternatively the behavior of a long and stiff ski during the rear rests present for the terminal phase of the turn.

Furthermore, document WO 95/00217 describes a double device intended to influence the stiffness characteristics of skis and their bending as a function of the supports exerted by the skier. This double device is constituted by two articulated interfaces mounted respectively under the stop and under the heel of the binding. Unfortunately, on the one hand, the system is very floating, which causes unacceptable losses of precision; on the other hand, the interfaces are symmetrical and cause practically the same effects when pressing forward and backward. Last but not least, the lever arms involved are far too short to generate significant forces.

Statement of the invention

The invention relates to a gliding board having a lower sliding face and an upper face intended to receive a safety binding capable of securing the user's shoe to the board, the board being equipped at the level of the fixings of a device. stiffener intended to modify the stiffness of the board under the effect of a push exerted by the user towards the upper face of the board.

• une plateforme supérieure allongée, destinée à recevoir la fixation sur sa face supérieure, ladite plateforme étant surélevée par rapport à la face supérieure de la planche et positionnée en porte à faux au-dessus de celle-ci ;
• au moins un point de liaison de la plateforme avec la face supérieure de la planche ;
• des moyens destinés à modifier la raideur de la planche de façon différenciée en fonction de la position, par rapport audit point de liaison, du point d'application de la poussée exercée par l'utilisateur sur la plateforme.

This gliding board is characterized in that the stiffening device comprises:

• an elongated upper platform, intended to receive the binding on its upper face, said platform being raised relative to the upper face of the board and positioned cantilevered above it;
• at least one point of connection of the platform with the upper face of the board;
• means intended to modify the stiffness of the board in a differentiated manner as a function of the position, relative to said connection point, of the point of application of the thrust exerted by the user on the platform.

The connection point is preferably located substantially at the level of the middle zone of the shoe.

In other words, the platform interposed between the binding and the board has a capacity of longitudinal inclination as a function of the location towards the front (at the start of the turn) or towards the rear (at the end of the turn). In this way, the platform cooperates with additional means making it possible to increase or reduce the stiffness of the board, depending on the phase of the turn.

In other words, thanks to the invention, an intrinsically stiff ski is helped in bending during the phases of initiation of a turn, that is to say when the force is exerted in front of the point of connection, which in turn makes behavior easier. Conversely, a naturally "flexible" ski is stiffened at the end of the turn, that is to say when the skier's load is exerted behind the middle position of the boot, which improves handling.

In a first embodiment, the point of connection of the platform with the board is situated substantially at the level of the middle zone of the shoe. It is in the form of an articulation pivot allowing the longitudinal inclination of the platform relative to the board.

Thus, the platform is tiltably mounted relative to the board and its inclination towards the front or towards the rear results directly from the thrusts located respectively towards the front or towards the rear.

• soit en partie localisés à l'arrière de la plateforme et sont aptes à bander la zone du ski située entre le pivot d'articulation et lesdits moyens ;
• soit en partie localisés à l'avant de la plateforme et sont aptes à faciliter le cintrage de la zone du ski située entre le pivot d'articulation et lesdits moyens ;
• soit encore localisés à l'avant et à l'arrière de la plateforme.

In various embodiments, the characteristic means intended to modify the stiffness of the board are:

• either partially located at the rear of the platform and are able to bandage the ski area located between the articulation pivot and said means;
• either partially located at the front of the platform and are able to facilitate the bending of the ski area situated between the articulation pivot and said means;
• is still located at the front and rear of the platform.

In this way, the characteristic means arranged towards the front of the platform make it possible to soften, when the turn is initiated, a moderately stiff ski, while when these means are arranged towards the rear, they allow the stiffening of the same ski.

Of course, it is better to combine these two effects to obtain optimal behavior.

Advantageously in practice, the characteristic means consist of cams implanted respectively on the platform and on the upper face of the ski, at least one of the cam surfaces being constituted by a sloping surface whose orientation is directed towards the front and towards the bottom.

In other words, the application of a vertical thrust is converted, by the relative sliding of the cam surfaces, into a longitudinal displacement of one of the parts of the platform. In a first case, this displacement causes a bringing together of fixed points on the ski, and therefore an aid in bending, while in another case, this displacement results in a spacing of fixed points on the ski, therefore a binding of the ski .

In a particular embodiment, one of these cam surfaces can be constituted by a cylindrical roller whose axis of revolution is parallel to the axis of articulation of the platform board.

In another embodiment, the characteristic means for modifying the stiffness of the board consist of a fulcrum from the rear of the platform on top of the rear of the board.

In other words, when the platform tilts backwards, the rear part of this platform exerts on the rear of the ski, a thrust directed perpendicular to the surface of the sole.

In a practical embodiment, the fulcrum consists of a plate forming a rear extension of the platform, the rear end of the plate being secured to the upper face of the ski. In other words, in this case, the rear end of the platform is connected and fixed to the upper face of the ski. In this way, during the inclination of the platform forward around its articulation pivot, the rear end of the platform tends to pull the board upwards and to induce bending. Conversely, during the rear supports, the tilting towards the rear of the platform repels this support point and causes the board to stiffen.

In an alternative embodiment, the fulcrum is integral with the edges of the ski.

In another embodiment, the connection between the platform and the top of the board is made by a plate interposed between the platform and the top of the board, behind the level of the middle zone of the shoe.

Thus, the front part of the platform is cantilevered. In this way, when the supports are directed forward, the front part of the platform tends to tilt, which causes the rear end of the platform to rise and thus bend the ski. Conversely, when the supports are directed towards the rear, the interposed characteristic plate allows the transmission of forces over a long length giving the skier a feeling of stiff and long skiing.

In this embodiment, the front end of the interposed plate can be likened to the articulation pivot.

To improve the comfort of the device, the interposed plate can be made of visco-elastic material with a hardness of the order of 80 Shore A minimum.

Brief description of the figures

The manner of carrying out the invention as well as the advantages which result therefrom will emerge clearly from the description of the embodiments which follow, supported by the appended figures in which:

Figure 1 is a simplified side view of the skate area of a ski equipped with the device according to the invention, in the absence of thrust exerted by the user.

Figures 2 and 3 are side views of the same device shown during an impulse exerted respectively forward and backward.

Figure 4 is a side view of an alternative embodiment of the invention, shown at rest.

Figures 5 and 6 are the representation of the deformations of the same device during pulses exerted respectively forward and backward.

Figure 7 is a side view of another alternative embodiment of the invention in which the front part of the platform is cantilevered.

Figure 8 is a side view of the device of Figure 7 shown with a forward-facing pulse.

Ways to realize the invention

As already said, the invention relates to a gliding board in general, but the description which follows only describes its application to an alpine ski, the transposition to another sliding sport being obvious for a skilled person. .

The invention therefore relates to a ski which has at its skate area a platform intended to receive a safety binding. The invention consists in providing this platform with complementary means making it possible to modify the stiffness of the ski, in a differentiated manner, when the skier exerts a vertical impulse towards the front or towards the rear of the platform.

Several architectures and localizations of these means allow to achieve the desired results.

In order to simplify the explanation, it is considered that the ski is placed horizontally flat, so that the pulses generated by the skier are vertical.

Example 1

In the embodiment illustrated in FIGS. 1 to 3, the board (1) receives at its skid zone, a platform (2) elongated and rigid on the upper face (3) of which the stopper (4) are arranged and the heel (5) responsible for maintaining the shoe (6) of the user.

This rigid platform (2) has, at the middle zone (7) of the boot (6), a transverse articulation axis (8) connecting it with a yoke (9) integral with the upper face (10) of the ski . Of course, this yoke (9) can be arranged inside a recess (not shown) made for this purpose on the upper face (10) of the ski. Furthermore, the articulation could also be achieved by reversing the relative positions of the axis (8) and the yoke (9), that is to say by mounting the yoke (9) under the platform (2) and by articulating it with respect to an axis integral with the ski.

This platform (2) has characteristic means in its front (11) and rear (12) end portions.

Thus, in the front part (11), the lower face (13) of the platform (2) has a sloping wedge (14) whose slope (15) is directed forward and downward. In addition, the upper face (10) of the ski has a sloping wedge (16) facing it, the slope (17) of which is identical to that (15) of the wedge (14) of the platform (2), and therefore oriented towards down and forward. It is obvious that one of these sloping shims (14, 16) can be replaced by another form of cam surface, in particular by a cylindrical roller (not shown) whose axis of revolution is transverse. In this way, the contact is not made over the entire surface of the sloping wedge but only by a generator of the roller.

In order to facilitate the sliding of these sloping wedges, they can be covered with a coating layer with a low coefficient of friction such as for example polytetrafluoroethylene.

Regarding the means (18, 19) arranged at the rear of the platform, these are of identical design to those mounted at the front of the platform, including the orientation of the slopes, directed downwards and towards the front.

The operation of this device is as follows.

When the skier is in a straight line, and no particular impulse is exerted by the skier, apart from his weight, the intermediate device is in the form illustrated in FIG. 1.

As already said, when initiating the turn, the skier tends to exert a localized vertical thrust (Fav) in front of the middle zone (7) of the boot (see Figure 2). This thrust (Fav) exerted in front of the articulation point (8) of the platform (2) naturally causes the inclination of the latter forward. In this way, the facing cam surfaces (15, 17) tend to slide, and given the orientation of their slope, the wedge (14) integral with the platform (2) is found further than that ( 16) mounted on the ski (1). In this way, the relative approximation, typically of the order of two millimeters, of this wedge (16) relative to the hinge yoke (9) causes the bending of the ski therefore a slight rise in the front part (20) ski. In this way, the contact area of the ski with the snow is reduced, which allows a better pivoting of the latter and a faster action in the turns.

In other words, a relatively stiff ski is "softened".

In contrast, Figure 3 shows what happens during a vertical impulse (Far) located towards the rear, observed at the end of the turn. This impulse (Far) causes the platform (2) to pivot and tilt backwards. This inclination causes the sliding of the rear cam surfaces (18, 19) and the appreciable separation of the sloping wedge secured to the ski (19) relative to the clevis (9) of articulation. This spacing results in the pulling of the back of the skid area resulting in an increase in its stiffness, even a slight bending downwards. Thus, the ski behaves as if it had a longer length which promotes driving and the end of the turn.

Example 2

The variant embodiment illustrated in FIGS. 4 to 6 operates according to another form of force transmission.

Thus, the rigid platform (2) receiving the binding is also articulated on a yoke (9) secured to the upper face (10) of the ski. The rear part (12) of the platform has a rigid extension (30) whose rear end (31) is fixed to the upper face (10) of the ski.

This extension (30) can be directly the rear part of the platform or can also consist of a bent steel or aluminum alloy blade of great rigidity.

The operation of this device is as follows.

During a vertical impulse (Fav) exerted forward, the platform (2) tends to tilt forward, and its rear end (12) tends to deviate from the board (1) . This spacing is kept constant relative to the ski thanks to the rear extension (30) of the platform (2). This inclination therefore causes the rear part (21) of the ski to be lifted and therefore bent upwards. In this way, and as already said, the effective area of contact with snow is reduced when the turn is initiated, which facilitates its behavior.

Conversely, during the final phases of the turn, the vertical pulses (Far) located towards the rear cause the platform (2) to tilt backwards. In this way, the yoke (9) and the extension (30) of the platform transmit this impulse (Far). This results in pressurization of the back of the skate area, or even a slight bending of the ski down. All this contributes to increasing the stiffness and the feeling of length of the ski during the driving phase and the end of the turn.

Example 3

The variant shown in FIGS. 7 and 8 relates to a platform (40), the front part (41) of which is cantilevered relative to the board.

This arrangement can be made, as illustrated, by the interposition of a rigid or semi-rigid plate (42) between the rear part (43) of the platform and the upper face (10) of the ski, but could also be done by two (or more) wedges inserted between the platform and the upper face of the ski, distributed behind the middle area of the boot (not shown).

The characteristic plate (42) or the shims, not shown, can advantageously be integrated into the platform (40).

Thus, when the skier exerts a vertical thrust towards the front of the boot, the front end (41) cantilevered from the platform tends to approach (e ₂ <e ₁ ) the upper face of the ski, and correlatively, the rear part of the platform tends to pivot around the front edge (45) of the plate (42), located in the vicinity of the middle zone of the boot, which causes the ski to bend upwards.

It appears from the above that the intermediate device according to the invention makes it possible to modify in a differentiated manner, the stiffness of the ski as a function of the location of the vertical thrusts exerted by the skier during a turn. It follows that skis and more generally gliding boards, equipped with such devices behave like skis of short length and flexible when initiating the turn and conversely like skis of greater stiffness and greater length in driving and ending phases of the turn. These dynamic modifications of the mechanical characteristics of the ski constitute the main advantage of the invention.

Claims (12)

Gliding board (1) having a lower sliding face and an upper face (10) intended to receive a safety binding (4, 5) capable of securing the shoe (6) of the user to the board (1), the board (1) being equipped at the level of the fasteners with a stiffening device intended to modify the stiffness of the board under the effect of a push exerted by the user towards the upper face (10) of the board, characterized in what the stiffening device includes: - an elongated upper platform (2), intended to receive the fixing (4, 5) on its upper face (3), said platform (2) being raised relative to the upper face (10) of the board and positioned in the door false above it; - at least one connection point (8, 45) of the platform (2) with the upper face (10) of the board; - Means (14-19; 30, 31; 42-45) intended to modify the stiffness of the board in a differentiated manner as a function of the position, relative to said connection point, of the point of application of the thrust (Fav , Far) exerted by the user on the platform (2). Gliding board according to claim 1, characterized in that the point of connection of the platform (2) with the board (1) is located substantially at the level of the middle zone (7) of the boot (6), in the form of pivot (8) for articulation allowing the longitudinal inclination of the platform (2) relative to the board. Gliding board according to claims 1 and 2, characterized in that the means (18, 19) intended to modify the stiffness of the board are partly located at the rear of the platform and are able to bandage the ski area located between the articulation pivot (8) and said means. Gliding board according to claims 1 and 2, characterized in that the means (14-17) intended to modify the stiffness of the board are partly located at the front of the platform and are able to facilitate the bending of the area of the ski situated between the articulation pivot (8) and said means. Gliding board according to claims 3 and 4, characterized in that the means intended to modify the stiffness of the board are located at the rear and at the front of the platform and are respectively capable of bandaging the ski area located at the rear of the articulation pivot and to facilitate the bending of the ski area located at the front of the articulation pivot. Gliding board according to one of claims 2 or 3, characterized in that the means consist of two facing cam surfaces (14-19), located respectively under the platform (2) and on the upper face (10) skiing, at least one of the cam surfaces being constituted by a sloping wedge (15, 17, 18, 19) whose orientation is directed forwards and downwards. Gliding board according to claim 6, characterized in that one of the cam surfaces is constituted by a cylindrical roller whose axis of revolution is parallel to the axis of articulation (8) of the board and the platform. Gliding board according to claim 2, characterized in that the means for modifying the stiffness of the board consist of a support point (31) at the rear (12) of the platform (2) on the top of the board. Gliding board according to claim 8, characterized in that the fulcrum consists of a plate (30) forming a rear extension of the platform (2), the rear end (31) of the plate being integral with the upper face (10) of the ski. Gliding board according to claim 8, characterized in that the fulcrum is integral with the edges of the ski. Gliding board according to claim 1, characterized in that the connection between the platform (2) and the upper face (10) of the board is produced by an interposed plate (42) between the platform (43) and the upper face of the board, its front edge (45) being located at the rear of the level of the middle zone (7) of the shoe (6). Gliding board according to claim 11, characterized in that the interposed plate (42) is made of visco-elastic material with a hardness of 80 Shore A minimum.

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